The present invention relates to needle instruments for obtaining tissue samples to be used for example in biopsy procedures. More particularly, the invention relates to improved instruments accommodating a variety of biopsy needle assemblies of differing gauges for sampling tissue.
In diagnostic tissue sampling, for example, of prostate tissue, needle assemblies have been developed which capture a longitudinal, or core sample of the tissue which is extracted for diagnosis. Conventionally, the needle assembly has a hollow outer cannula needle which cooperates with an inner stylet needle to cut and capture a core of the tissue within a notch formed in the inner stylet as described for example in U.S. Pat. No. 5,121,751, the text of which is incorporated by reference herein, and which illustrates an operating mechanism for a biopsy needle assembly. Typically, a different instrument is required for the various diagnostic procedures. For example, the biopsy needle assemblies for prostate biopsies are much larger than those used for breast biopsies. In both instances, however, the same operating instrument or mechanism may be employed to attain movement of the cannula and stylet needles of the assembly. As such, it is desirable to support the needle assembly properly during the biopsy procedure, and avoid undesired movement of the needles which may have been previously positioned using sophisticated imaging equipment. The problem of supporting biopsy needles of differing sizes is eliminated with an instrument constructed in accordance with the present invention.